Position Tracking Error Constrained Super-Twisting Dynamic Surface Control with Disturbance Observer for Robot Manipulators

A tracking error constrained dynamic surface control (DSC) with a super-twisting algorithm (STA) and a nonlinear disturbance observer is proposed for robot manipulator systems, where the system dynamics are partially known. The stabilizing controls of the DSC were designed by combining the STA with the virtual tracking errors defined from the DSC design concept. A nonlinear disturbance observer was designed to estimate the unknown nonlinear function and external disturbance instead of using parameterization of the nonlinear function or adaptive law in the conventional STA and DSC schemes. Moreover, a simpler tracking error constraint method is also proposed. The proposed tracking error constrained STA-DSC scheme combined with a nonlinear disturbance observer has better tracking error performance and robustness to uncertainty of robot manipulator system than control systems with a conventional DSC and disturbance observer. The control scheme was evaluated through simulations with the articulated manipulator system.